[dev.typeparams] cmd/compile/internal/types2: remove Type.Under method in favor of function

This removes the need for the aType embedded type and brings the types2.Type
API in sync with the go/types.Type API.

For reasons not fully understood yet, introducing the new under function
causes a very long initialization cycle error, which doesn't exist in
go/types. For now, circumvent the problem through a helper function variable.

This CL also eliminates superflous (former) Under() method calls
inside optype calls (optype takes care of this).

Plus some minor misc. cleanups and comment adjustments.

Change-Id: I86e13ccf6f0b34d7496240ace61a1c84856b6033
Reviewed-on: https://go-review.googlesource.com/c/go/+/293470
Reviewed-by: Robert Findley <rfindley@google.com>
Trust: Robert Griesemer <gri@golang.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/src/cmd/compile/internal/types2/conversions.go b/src/cmd/compile/internal/types2/conversions.go
index c9603b263c..dc0621919e 100644
--- a/src/cmd/compile/internal/types2/conversions.go
+++ b/src/cmd/compile/internal/types2/conversions.go
@@ -90,8 +90,8 @@ func (x *operand) convertibleTo(check *Checker, T Type) bool {
 
 	// "x's type and T have identical underlying types if tags are ignored"
 	V := x.typ
-	Vu := V.Under()
-	Tu := T.Under()
+	Vu := under(V)
+	Tu := under(T)
 	if check.identicalIgnoreTags(Vu, Tu) {
 		return true
 	}
@@ -100,7 +100,7 @@ func (x *operand) convertibleTo(check *Checker, T Type) bool {
 	// have identical underlying types if tags are ignored"
 	if V, ok := V.(*Pointer); ok {
 		if T, ok := T.(*Pointer); ok {
-			if check.identicalIgnoreTags(V.base.Under(), T.base.Under()) {
+			if check.identicalIgnoreTags(under(V.base), under(T.base)) {
 				return true
 			}
 		}
@@ -146,7 +146,7 @@ func isUintptr(typ Type) bool {
 
 func isUnsafePointer(typ Type) bool {
 	// TODO(gri): Is this asBasic(typ) instead of typ.(*Basic) correct?
-	//            (The former calls typ.Under(), while the latter doesn't.)
+	//            (The former calls under(), while the latter doesn't.)
 	//            The spec does not say so, but gc claims it is. See also
 	//            issue 6326.
 	t := asBasic(typ)